Variable area jet propulsion nozzles



June 27,1961 J. M. s. KEEN 2,990,029

VARIABLE AREA JET PROPULSION NOZZLES Filed March 15, 1957 v 9Sheets-Sheet 1 June 27, 1961 J. M. s. KEEN VARIABLE AREA JET PROPULSIONNOZZLES 9 Sheets-Sheet 2 Filed March 15, 1957 June 27, 1961 J. M. s.KEEN 2,990,029

VARIABLE AREA JET PROPULSION NOZZLES Filed March 15, 1957 9 Sheets-Sheet3 June 27, 1961 J. M. s. KEEN 2,990,029

VARIABLE AREA JET PROPULSION NOZZLES Filed March 15, 1957 9 Sheets-Sheet4 June 27, 1961 s, EE 2,990,029

VARIABLE AREA JET PROPULSION NOZZLES Filed March '15, 1957 9Sheets-Sheet 5 June 27, 1961 J. M. s. KEEN VARIABLE AREA JET PROPULSIONNOZZLES 9 Sheets-Sheet 6 Filed March 15, 1957 June 27, 1961 J. M. s.KEEN 2,990,029

VARIABLE AREA JET PROPULSION NOZZLES 9 Sheets-Sheet 7 Filed March 15,1957 K it II; I

June 27, 1961 J. M. s. KEEN 2,990,029

VARIABLE AREA JET PROPULSION NOZZLES Filed March 15, 1957 SSheets-Sheet8 June 27, 1961 s, E 2,990,029

VARIABLE AREA JET PROPULSION NOZZLES Filed March 15, 1957 9 Sheets-Sheet9 United States Patent 2 990 029 VARIABLE AREA JET iRoPULsIoN NOZZLESJohn Michael Storer Keen, Allestree, England, assignor to Rolls-RoyceLimited, Derby, England, a British com- Filed Mar. 15, 1957, Ser. No.646,498 Claims priority, application Great Britain Mar. 16, 1956 8Claims. (Cl. 181-41) This invention comprises improvements in orrelating to variable area jet nozzles for jet propulsion purposes.

According to the present invention a jet nozzle for jet propulsionpurposes comprises a tubular wall member defining a gas passage andhaving an outlet at one end, and at least one flap member which isadjustable between a first position in which it projects into the gaspassage upstream of the outlet .to define a first effective area of thenozzle less than the area of said outlet of the tubular wall member, anda second position in which it is retracted and the nozzle has a secondeffective area greater than said first effective area, and the totalperipheral extent of such flap members being a minor proportion of thetotal peripheral extent of the nozzle outlet.

According to a feature of the invention in the second position of theflap member or members, the second effective area is substantially equalto the area of said outlet.

According to another feature of the present invention each flap membermay extend axially of the nozzle and be pivoted to the tubular member toswing about an axis substantially tangential to the tubular member, saidaxis being at a distance upstream from said outlet greater than theaxial extent of the flap member.

According to yet a further feature of the present invention provision ismade for substantially equalizing (the pressures on each side of theflap member or flap members. The flap member or members may haveassociated therewith gas sealing structure to prevent the substantialflow of gas around the sides of the flap member or members, whileadditional gas sealing structure may be provided associated with thedownstream end of the flap member or flap members, thereby to provide aclosed chamber, provision being made for gas communication from theinterior of the tubular wall member into said chamber thereby tosubstantially equalize the pressures on the two sides of the flap memberor flap members.

In preferred embodiments of the invention a flap member or flap membersmay occupy a cut-out in the tubular member, said cut-out being closed bya blister housing. Further, the tubular wall member may have projectingWithin it for each flap member a pair of parallel walls which extendsubstantially parallel to a plane containing the nozzle axis.

In certain preferred embodiments a pair of flap members are providedarranged at diametrically opposite posi tions around the tubular wallmember. In another preferred embodiment about six flap members areprovided disposed equi-angularly about the tubular wall member.

In yet another preferred embodiment the tubular wall member is providedwith a series of fixed structures angularly spaced around its innersurface and projecting within it to define a series of gas-flowchannels, and having such flap members arranged to project within thechannels between the fixed structures. In the latter preferredembodiment it will be noted that when the adjustable flap members are inthe position in which the area of the nozzle is reduced below themaximum, the nozzle is of corrugated form, the corrugations increasingin depth from the upstream to the downstream end, and accordingly thenozzle will have the property when adjusted to positions other than themaximum area position of re- 2,990,029 Patented June 27, 1961 ducing theintensity of noise as more fully described in Rolls-Royce British PatentNo. 768,553.

A number of constructions of variable-area jet nozzle will now bedescribed with reference to the accompanying drawings, in which:

FIGURE 1 is an end view in part of one construction of nozzle,

FIGURE 2 is a section to a larger scale on the line 22 of FIGURE '1,

FIGURE 3 is a partial plan view of one part of a flap member,

FIGURE 3A is a partial plan view of the other part of a flap member,

FIGURE 4 is a section on the line 4-4 of FIGURE 2,

FIGURE 5 is a section on the line 5-5 of FIGURE 2,

FIGURE 6 is a view corresponding to FIGURE 2 of a second construction ofnozzle,

FIGURE 6A is a plan view of a part of the nozzle shown in FIGURE 6,

FIGURES 7 and 8 are sections on the lines 7-7, 88 of FIGURE 6,

FIGURE 9 is an end view of another construction of nozzle.

FIGURE 10 is a view corresponding to FIGURE 9 of yet anotherconstruction of nozzle, and

FIGURE 11 is a section on the line 11-11 of FIG- URE 10.

Referring first to FIGURES l and 2, the variable-area jet nozzlecomprises a frusto-conical wall 10 with its smaller end downstream toform the throat of the nozzle, a pair of longitudinal flap members 11(one only of which is shown, the second being at a positiondiametrically opposite the first) by which the area of the throat isvaried, and power means to move the members 11. The two flap membershave a combined peripheral extent which is a minor proportion of thetotal peripheral extent of the nozzle outlet.

The wall 10 has cut-outs 12 at the positions of the flap members 11,each cut-out extending upstream from the outlet end of the nozzle, andeach cut-out 12 is covered by an external blister housing. The blisterhousing is formed by a pair of flanged sheet-metal pieces 13a, 13b ofwhich the piece 13a is secured to the wall '10 on the upstream side ofthe cut-out, and of which the piece 13b is secured to a fully annularstrengthening ring 14 which is secured to wall 10 at the outlet end ofthe nozzle, and by a cover piece 15 which is secured to the outer edgesof the walls 13a, 13b and is secured at its circumferentially spacededges to the wall 10 in such a manner as to be tangential thereto.

Each flap member 11 is formed in two parts which are pivotally mountedon the wall 10 so as to be capable of relative angular movement, thepivotal axis being positioned at a distance upstream of the nozzleoutlet greater than the axial extent of the flap member.

The first part comprises (FIGURES 2, 3 and 5) a central girder member 16having secured to it a sheetmetal piece 17 which affords alongitudinally and circumferentially-extending inner wall of theadjustable member and which is shaped so that in the angular position ofthe pant in which the nozzle area is a maximum, it substantially fillsthe cut-out 12 and conforms to the curvature of the wall 10. The innerwall piece 17 has secured on its upper surface a rectangular, L-sectionsheetmetal piece the four upwardly-projecting sides of which form innerportions 18a of a pair of outwardly-extending lateral walls of the flapmember 11, an inner portion 18:) of a downstream wall of the member andan inner portion of a forward wall. The wall portions 18a, 18b, 18cdefine a well space. The girder member 16 has secured to it at itsupstream end a lug having a bored boss 19, the ends 1911 of the bore inthe boss being enlarged to receive a needle bearings 20 (FIGURE 4) bywhich the part is pivoted on a spindle 21 supported in a bracket 22secured on the forward wall 13a of the blister housing. The girdermember 1 6 also carries at a point intermediate its ends a pair of boredalinged bosses 23 (FIGURE the purpose of which will appear below. Itwill be seen that the upstream edge 17a of the inner wall 17 is curvedoutwardly (FIGURE 2) away from the nozzle axis and has a number oftongues (FIGURE 3) to extend between the lugs of bracket 22, and thatthe downstream edge of this wall projects beyond the downstream wall 18b(FIG-- URE 2).

The second part is of U-form in plan and comprises spaced top and bottomwalls 24a, 24b respectively (FIG- URES 3 and 5), side walls 240 whichform outer portions of the lateral walls of the flap member 11, a rearwall 24d which forms the base of the U and forms the outer portion ofthe downstream wall, and forward walls 24a which forms the ends of thelimbs of the U. The second part is adapted to be received with a slightclearance in the well space formed by the walls 18a, 18b, 180. The endsof the limbs of the second part carry brackets 25 with bored bosses 25aat their ends, the bores in the bosses receiving needle bearings 26 bywhich the part is mounted on the spindle 21 (FIGURE 4). The second partalso has secured to it a pair oi hollow bushes 27 (FIGURE 5), one ineach limb, the bushes being carried in box-like structures 27a weldedbetween the top and bottom walls 24a, 24b, and being aligned with oneanother.

The power means for moving the flap members comprises a pair ofhydraulic or pneumatic rams, one for each flap member, Each ram (FIGURE2) is mounted on the forward wall 13a of the associated blister housingand comprises a ram cylinder 30, externally of the housing, a piston 31working in the cylinder 30, a piston rod 32 connected to the piston 31and extending into the blister housing; a piston rod shroud 33 which issecured to the cylinder 30, extends axially into the blister housingaround the piston rod and has at its end remote from the cylinderlateral slots 33a (FIGURE 5) through which extends a crosshead 34. Thecrosshead 34 is connected by a swinging link 35 to a pin 36 which isengaged in the bosses 23 carried by the girder member 16. The link 35 isin two pieces secured together by a setscrew 35a. The crosshead 34 hasalso pivoted to it at its ends a pair of swinging links 37, the oppositeends of which engage pivotally on pins 38 mounted in the bushes 27.

The end of the piston rod 32 remote from the piston 31 is reduced indiameter as indicated at 32a and the reduced-diameter portion slidinglyengages in a bush 39a mounted in the end of the piston rod shroud 33,while the main portion of the piston rod 32 slidingly engages in a bush3% separated from bush 39a by a slotted spacer member 39c formed by alength of tube having a pair of slots 39d in it to permit the passage ofthe cross-head 34.

The travel of the piston 31 within the cylinder is determined in onedirection by abutment of the end of the piston rod 32 on which thepiston 31 is mounted, with a projection 40 from the end cover 41 of thecylinder 30, and the travel of the piston in the opposite direction islimited by abutment between the piston and a facing 42 provided on theend of the piston rod shroud 33 which is within the cylinder 30. Theextent by which the piston rod can project into the blister housing isvaried by providing a shim 30a between the end of the cylinder 30 andthe wall 13a. The shim provides the means by which the anti-clockwiseswinging of the flap member is adjusted.

The drawings show the flap members 11 in the operative position, that isthe position in which they are effective to reduce the outlet area ofthe nozzle, and it will be seen that, in this position of the flapmembers, the walls 17 diverge from the wall in the downstream directiontowards the axis of the nozzle and also that the wall portions 24c, 24dform outward continuations of the lateral walls 18a and downstream wall1812 respectively of the first part of the flap member. On moving thepiston 31 to the right as viewed in FIGURE 2, the parts of the flapmember 11 are caused to swing upwardly until the inner Wall 17 of thefirst part of the adjustable member lies snugly within the cut-out 12.In this position of the a parts, the second part is nested within thefirst part so that the radial extent of the flap member beyond theoutside of the nozzle is substantially less than the extent to which theflap member extends within the gas passage through the nozzle when inthe operative position.

It is also arranged that the static pressures on each side of the innerwall 17 are balanced so that a lighter construction of the flap memberscan be employed and so that the operating loads necessary in moving theflap members to the position shown in the drawings are reduced. Thepressure balancing is effected by leaving a slight gap between theupstream edge of the cut-out 12 and the upstream edge of the inner wall17. if desired as shown in FIGURE 3 small holes 17b may be drilled inthe wall 17 for pressure-balancing purposes, the size being such thatthe flow through them is relatively small.

The ram cylinders 30 of the two adjustable members are coupled togetherfor simultaneous operation. For instance, as shown, the pressure fiuidsupplied to the cylinders of the two rams may be effected through thepipes 43 (FIGURE 1) leading from a supply control valve 44. The supplyto the left-hand ends of the cylinders may be eifected through pipesextending from the valve 44 around one side of the nozzle and the supplyto the right-hand ends may be effected through pipes lying parallel tothe above-mentioned pipes.

Referring now to FIGURES 6 to 8, the nozzle illustrated comprises atubular wall 50 having a pair of cutouts 51 (of which one only is shown)located respectively at diametrically-opposite points in the nozzle andalso having a flanged machined ring 52 welded to the outlet end of theconical wall. A sheet-metal blister 53 having a front wall 53a, a rearwall 53b and top wall 530 is secured to the external surface of theconical wall 50 around the edge of each cut-out to define a housingspace fior a pair of flap members for adjusting the outlet area of thenozzle. The rear wall 53b has a flange 53d which fits against the innersurface of the ring 52 and extends circumferentially between thecircumferentially-spaced edges of the cut-out 51.

A bracket 54 is secured to the internal surface of each wall 53:: andhas the respective nozzle area adjusting flap member pivoted thereto bya pivot pin 55.

Each flap member extends longitudinally and is fiormed in two partswhich are capable of relative pivoting to permit adjustment of the partsof the flap member between the full line position shown (in which thenozzle area is a minimum) and the chain line position (in which thenozzle area is maximum).

The first part comprises a central back-bone structure 57 carrying lugs58 receiving the pin 55, a longitudinally andcircumferentially-extending sheetsrnetal inner wall 61 which is curvedto correspond to the curvature of the conical wall 50 so that in thechain line position the wall 61 fits in the cut-out 51, a front wall 59and rear wall 60, and a pair of side walls 62 extending longitudinallyalong the side edges of the inner wall 61 and joining the front and rearwalls 59, 60. Ihe inner wall 61 projects slightly beyond the rear wall60.

The second part of the flap member (FIGURE 6a) comprises U-shaped innerand outer walls 63, 64 respec tively, front walls 63a carrying lugs 63bto receive the pin 55, a rear wall 65 and side walls 66 extending fromthe front wall 63a to the rear wall 65. The walls 63, 63a, 65, 66 may bein one piece and the Wall 65 may be a separate piece welded to flanges67 on the front, rear and side walls.

Pivoting of the parts of the flap member is effected by means of apneumatic ram whereof the cylinder 68 is externally of the blisterhousing 53 and is secured to the wall 53a thereof. The ram piston rod 69projects into the blister housing 53 and carries a cross-pin 70. The pin70 carries rollers 71 which run on tracks afforded by flanges 72 formingpart of a channel member 73. The channel member 73 is supported at oneend in a slide bracket 74 secured by studs 75 to the wall 53c of theblister housing 53, and at its other end is secured to the wall 53athrough which the piston rod 69 projects. The roller arrangementrelieves the piston rod of side loads.

The pin 70 has a pair of links 76 pivoted to it, one on each side of thepiston rod 69, and the opposite ends of the links 76 are pivoted on apin 77 mounted in stifiner bars 78 secured to the backbone structure 57of the first part of the flap member. Thus, when the piston rod 69 isretracted, the first part of the flap member is caused to swing betweenthe full line and chain line positions.

The links 76 have pivoted to them at points between their ends a furtherlink 79, the opposite end of which is pivoted by a pin 80 in brackets 81secured to the outer wall 64 of the second part of the flap member. Thearrangement is such that, during movement of the first flap part, thesecond flap part moves, as will be seen from its full line and chainline positions, to a less angular extent than the first part.

In the full line positions, the side walls 66 and rear wall 65 of thesecond flap part form outward continuations of the side walls 62 andrear Wall 60 respectively of the first flap part, and in the chain linepositions the second flap part is received snugly in the first flap partand the Whole flap member is received in the blister housing thus havinga less radial projection externally of the nozzle than the extent ofprojection of the flap member into the nozzle when the flap member is inits full line position.

The pressure in the blister housing 53 is equalized with that within thenozzle by providing holes 82 in the conical wall 50 which open into thehousing.

As in the first-described construction, the combined peripheral extentof the flap members is a minor proportion of the total peripheral extentof the nozzle outlet.

Refem'ng now to FIGUR'E 9, there is illustrated a nozzle which isconstructed not only to have a variable outlet area but also to besilenced in operation.

The nozzle comprises an outer tubular member 90 to the inner surface ofwhich is secured a series of six closed structures 91 defining acorresponding series of angular-lyspaced channels 92 for the exhaust gasdisposed about a central core 93. The dimensions of the tubular member90 and structures are selected so that the total cross-sectional areaavailable for flow decreases towards the outlet of the nozzle. Thedivision of the issuing gas, at least peripherially, into a number ofstreams has the effect of markedly reducing the noise generated inoperation of the nozzle, as compared with, say, a plain frustoconicalnozzle.

In order to permit the eifective outlet area to be varied betweenmaximum and minimum values, the nozzle is provided at diametricallyopposite points with adjustable flap members 94, which may beconstructed as described with reference to FIGURES l to or FIGURES 6 to8. It will be seen that the flap members 94 when extended occupy part ofa pair of the channels 92. Also the combined peripheral extent of thetwo flap members 94 is a minor proportion of the total peripheral extentof the nozzle outlet.

Another arrangement is shown in FIGURES and 11, in which the nozzlecomprises a tubular part 100 (corresponding to the part 10 of the firstdescribed construction) with a series of, say six, pairs of parallelwalls 101 extending inwardly from the edges of cut-outs 101a. The walls101 forming a pair are parallel to a plane containing the nozzle axisand the centre line of a flap member 102 of curved section which isdisposed between the pair of walls 101 and is mounted on the tubularmember adjacent the upstream ends of the walls 101 by a pivot pin 103.The radial depth of the walls 101 increases in the downstream direction.The flap member 102 is actuated by a ram 104 through a link 105connected to the ram piston rod 106. The ram is mounted on the exteriorof a blister housing 107 and its piston rod 106 projects into thehousing 107.

In one position, the flap members 102 occupy the cutouts 101a in thetubular member and the nozzle area is a maximum, and in a secondposition the flap members 102 have their edges coincident with the inneredges 101b of the walls 101 and the nozzle outlet area is a minimum. Inthe second position of the flap members a substantial silencing etfectis obtained as compared with an equivalent plain frusto-conical nozzle.

-As in the previous constructions, the flap members have a combinedperipheral extent which is a minor proportion of the total peripheralextent of the nozzle outlet.

It will be appreciated that the flap members 102 travel over the surfaceof each of the parallel walls 101 when they are moved from theinoperative to the operative position.

In this case the flap members will be pressure-balanced as described inrelation to the first embodiment.

The number of adjustable members may be varied; for example, there maybe one or two adjustable members where lightness and simplicity aredesired, or there may be say six adjustable members, as shown in FIGURES10 and 11. In this latter case, when the adjustable members are in theoperative position in which the area of the nozzle is reduced below themaximum, the nozzle is of corrugated form, the corrugations increasingin depth from the upstream to the downstream end, and accordingly suchan adjustable-area nozzle will have the property, when adjusted topositions other than the maximum area position, of reducing the level ofnoise produced by the jet stream as more fully described in BritishPatent No. 768,553.

I claim:

1. A jet propulsion nozzle for a continuous combustion jet propulsionengine, which nozzle comprises a rigid tubular wall member having anoutlet at one end and defining a gas passage through which exhaust gasesflow from the engine to the outlet, said gas passage having across-sectional area which decreases from the upstream end of the nozzletowards the outlet at least over part of its axial length, at least onelongitudinally-extending flap member accommodated within the tubularwall member, and pivot means supporting the flap member at its upstreamend from the tubular wall member to swing about an axis substantiallytangential to the tubular wall member between first and secondpositions, said flap member including a longitudinallyandcircumferentially-extending wall extending axially downstream from saidpivot means, which longitudinallyand circumferentially-extending wall insaid first position projects into said gas passage and reduces theeffective area of the nozzle and which in said second position isretracted flush with the tubular wall member and forms substantially asmooth continuation of said tubular wall member, said tubular wallstructure including walls extending externally of the said flap memberand defining with the longitudinally and circumferentially-extendingwall of the flap member a chamber closed oil from atmosphere, saidchamber being in communication with the gas passage whereby the pressurewithin the chamber is substantially equal to the pressure of the gasstream and thus the pressures on each side of said longitudinallyandcircumferentially-extending wall are equalized.

2. A jet propulsion nozzle according to claim 1 having said pivot meanspositioned at a distance upstream of the outlet greater than thelongitudinal extent of the flap member.

3. A jet propulsion nozzle for a continuous combustion jet propulsionengine, which nozzle comprises a rigid tubular wall member having anoutlet at one end and defining a gas passage through which exhaust gasesflow from the engine to the outlet, said gas passage having across-sectional area which decreases from the upstream end of the nozzletowards the outlet at least over part of its axial length, at least onelongitudinally-extending flap member accommodated within the tubularwall member, and pivot means supporting the flap member at its upstreamend from the tubular wall member to swing about an axis substantiallytangential to the tubular wall member between first and secondpositions, said flap member including a longitudinallyandcircumferentially-extending wall extending axially downstream from saidpivot means, and parallel walls extending outwards from the edges ofsaid longitudinallyand circumferentially-extending wall, whichlongitudinally-and circumferentially-extending wall in said firstposition projects into said gas passage and reduces the effective areaof the nozzle and which in said second position is retracted flush withthe tubular wall member and forms substantially a smooth continuation ofsaid tubular wall memher, said tubular wall structure including wallsextending externally of the said flap member and defining with thelongitudinally and circumferentially-extending wall of the flap member,a chamber closed off from atmosphere, said chamber being incommunication with the gas passage whereby the pressure within thechamber is substantially equal to the pressure of the gas stream andthus the pressures on each side of said longitudinally andcircumferentially-extending wall are equalized, said flap member beingmade in two parts, the first part comprising said longitudinally andcircumferentially extending wall and inner portions of the parallelwalls, and the second part. comprises outer portions of said parallelwalls and the parts swing to different angular extents so that, when theflap member is in said second position, the second part is nested withinthe first part, and that when the member. is in the first position theouter portions of the parallel walls form outward extensions of theinner portions.

4. A jet nozzle according to claim 1 wherein in said second positionsaid flap member occupies a cut-out in the tubular wall member, and saidwalls provided externally of the tubular wall member constituting ablister housing covering said cut-out.

I 5. A jet nozzle according to claim 1 wherein said flap membercomprises parallel walls extending outwards from the edges of saidlongitudinally and circumferentially-extending wall of the flap member.

6. A jet nozzle according to claim 3 wherein each part of the flapmember also comprises a rear wall portion joining the downstream edgesof the parallel wall portions, said rear wall portions formingcontinuations one of the other in the first position of the flap member.

7. A jet nozzle according to claim 1 comprising a pair of such flapmembers arranged at diametrically opposite positions around the tubularwall member.

8. A jet nozzle according to claim 1 comprising also a series of fixedstructures angularly spaced around the inner surface of the tubular wallmember and projecting within it to define a series of gas flow channels,and having said flap member arranged to project within the channelbetween a pair of fixed structures.

References Cited in the file of this patent UNITED STATES PATENTS Meyeret a1. May 13, 1947

